Temperature-dependent interfacial chemical bonding states and band alignment of HfOxNy/SiO2/Si gate stacks

Temperature-dependent interfacial chemical bonding states and band alignment of HfOxNy/SiO2/Si gate stacks have been investigated by X-ray photoemission spectroscopy (XPS) and spectroscopic ellipsometry (SE). By means of the chemical shifts of Hf 4f, Si 2p, O 1s, and N 1s core-level spectra, it has been found that the chemical stability of the HfOxNy/SiO2/Si stacks strongly depends on the annealing temperature. Analysis of temperature-dependent band alignment of HfOxNy/SiO2/Si stacks suggests that the valence band offset Delta E-v increases slowly from 1.82 eV for as-grown film to 2.55 eV for annealed film at 700 degrees C; however, the values of conduction band offset Delta E-c only demonstrates a slight change in the vicinity of 1.50 eV. From the band offset viewpoint, HfOxNy/SiO2/Si gate stack could be a promising candidate for high-k gate dielectrics. (c) 2007 American Institute of Physics.